Iron-type golf club head and production method therefor

ABSTRACT

An iron-type golf club head 1 can elongate a travelling distance of balls for a long iron and can enable the better controlling of balls for a short iron. A head body 8, having a face 3, is formed from one material, while a hosel 7 formed from another material having the different specific gravity than that of the head body 8. For long irons, the material of the hosel 7 is denser than that of the head body 8, while for short irons, the material of the head body 8 is denser than that of the hosel 7. A friction welding process may be used to join the head body 8 to the hosel 7.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to an iron-type golf club and a productionmethod therefor.

(b) Description of Prior Art

Generally, a golf club is comprised of a head and a shaft, classifiedinto three types, i.e., wood, iron and putter.

Iron golf club is further classified according to an angle of loft (loftangle). Iron golf club having a smaller loft angle (e.g., 20 to 30degrees), is designated long iron, while iron golf club head having alarger loft angle (e.g., 40 to 50 degrees) designated short iron. Ingeneral, iron golf club is numbered, beginning at short iron toward longiron, such as 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 9th, PW (pitchingwedge), SW (sand wedge) and LW (lob wedge) or the like.

Conventionally, there are two types of iron golf club heads in terms ofits structure, one is so-called cavity-back iron, having a face forstriking balls and a back, the other so-called solid-back iron, having asmoothed back. Such golf club heads have one of the most importantattributes thereof or so-called a sweet spot in a certain area on theface.

In the past, there has been proposed an iron golf club head, in FIG. 1of Japanese Patent Appln Laid-Open No. 7-144029, wherein the weight inthe outer periphery of the head is adjusted so that the center ofgravity of the head may be consistent with the geometrical center on theface or the position at which balls are expected to be struck.

Whereas, for an iron golf club head, contradictory performances arerequired, i.e., allowing balls to travel a longer distance and at thesame time permitting of the better-controlling of the travellingthereof. Long iron is for such longer-distance travelling, while shortiron for better control of balls. According to the prior iron golf clubhead, there has been proposed the change of the configuration of thecavity, which, however, would set limit to satisfy the desiredperformances.

SUMMARY OF THE INVENTION

To eliminate the above-mentioned problems, it is, therefore, a mainobject of the present invention to provide an iron-type golf club headof which long iron enables noticeably elongating of the travellingdistance of balls, while short iron permits the better control of balls.

It is another object of the present invention to provide a productionmethod for such iron-type golf club head.

According to a major feature of the present invention, there is providedan iron-type golf club head having a face at its front and a hosel atits one side for mounting a shaft thereto, which comprises a head bodyhaving said face, said head body being formed from a material having aspecific gravity different than that of a material for said hosel.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the invention will be apparentto those skilled in the art from the following description of thepreferred embodiments of the invention, wherein reference is made to theaccompanying drawings, of which:

FIG. 1 is an exploded perspective view showing a first embodiment of theinvention.

FIG. 2 is a section showing a first embodiment of the invention.

FIG. 3 is a perspective view showing a first embodiment of theinvention.

FIG. 4 is an explanatory front view illustrating a player's swingingstance in the case of a first embodiment.

FIG. 5 is an exploded perspective view showing a second embodiment ofthe invention.

FIG. 6 is a section showing a second embodiment of the invention.

FIG. 7 is an exploded prspective view showing a third embodiment of theinvention.

FIG. 8 is a section showing a third embodiment of the invention.

FIG. 9 is an exploded perspective view showing a fourth embodiment ofthe invention.

FIG. 10 is a section showing a fourth embodiment of the invention,illustrating a golf club head in a joined state.

FIG. 11 is a perspective view showing a fourth embodiment of theinvention.

FIG. 12 is an exploded perspective view showing a fifth embodiment ofthe invention.

FIG. 13 is a section showing a fifth embodiment of the invention,illustrating a golf club head in a joined state.

FIG. 14 is a section showing a sixth embodiment of the invention,illustrating a golf club head in a joined state.

FIG. 15 is a section showing a seventh embodiment of the invention,illustrating a golf club head in a joined state.

FIG. 16 is a section showing an eighth embodiment of the invention,illustrating a golf club head in a joined state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter is described a first embodiment of a golf club head of theinvention with reference to FIGS. 1 to 4.

An iron golf club head comprises a head 1 and a shaft 2. The head 1 hasa face at its front, a recess 4 called a cavity at its back, a sole 5 atits bottom, a heel 6 at its one side of the bottom and a hosel 7 forattaching shaft 2 thereto at the same side thereof. The head 1 comprisesa head body 8 formed with said face 3, recess 4, sole 5 and heel 6, andthe short-cylinder-shaped hosel 7, which being formed of material ofdifferent specific gravities by forging in advance, and the head body 8and the hosel 7 being integrally combined.

An upper part of the one side of the head body 8 is formed with a femalethreaded hole 9, into which is screwed a male screw 10 formed at a lowerpart of the hosel 7, while into a mounting hole 11 formed at an upperpart of the hosel 7 is inserted the shaft 2, thus assembling aniron-type golf club head.

The head 1 has the following dimensions of a loft angle A and a lengthof a club, corresponding to the iron number.

                  TABLE 1                                                         ______________________________________                                                   LOFT ANGLE    LENGTH OF CLUB                                       IRON NUMBER                                                                              (degree)      (inch)                                               ______________________________________                                        1          14-17, preferably 15                                                                        39.5-40, preferably 39.5                             2          17-20, preferably 18                                                                        39-39.5, preferably 39                               3          20-23, preferably 21                                                                        38.5-39, preferably 38.5                             4          23-26, preferably 24                                                                        38-38.5, preferably 38                               5          26-30, preferably 28                                                                        37.5-38, preferably 37.5                             6          30-34, preferably 32                                                                        37-37.5, preferably 37                               7          34-38, preferably 36                                                                        36.5-37, preferably 36.5                             8          38-42, preferably 40                                                                        36-36.5, preferably 36                               9          42-46, preferably 44                                                                        35.5-36, preferably 35.5                             PW         46-50, preferably 48                                                                        35-35.5, preferably 35                               W          50-54, preferably 52                                                                        35-35.5, preferably 35                               SW         54-58, preferably 56                                                                        34.5-35.5, preferably 34.5                           LW         58-62, preferably 60                                                                        34.5-35.5, preferably 34.5                           ______________________________________                                    

For the long irons of the 1st to 5th irons in the above Table 1, steel(the specific gravity:approx. 7.9) is chosen as the material for thehead body 8, while titanium or titanium alloy the specificgravity:approx. 4.5) for that for the hosel 7. Thus the specific gravityof the material for the hosel 7 is smaller than that for the head body8.

On the other hand, for the short irons of the 6th to 9th irons W, SW andLW in the above Table 1, steel (the specific gravity:approx. 7.9) ischosen as the material for the head body 8, beryllium copper alloy (thespecific gravity:approx. 8.2) for the hosel 7. Thus, the specificgravity of the material for the hosel 7 is larger than that for the headbody 8. Incidentally, reference numeral 12 designates so-called scorelines formed on the face 3.

Next, the action of the above-structured golf club head will bedescribed.

For long irons, as the hosel 7 is formed of the material thinner thanthat for the head body 8, the center of gravity G₁ of the head 1 can belocated at the opposite side to the heel 7, and relatively downward, ascontrasted to the conventional long irons each having the head bodyintegrally combined with the hosel, both being formed of steel.Accordingly, the orbital radius R in swinging can be enlarged, therebyincreasing moment of inertia. As a result, larger striking impact can beimparted to balls B so as to make them travel a longer distance.

For short irons, as the hosel 7 is formed of the material denser thanthat for the head body 8, the center of gravity G₂ of the head 1 can belocated at the side proximate to the heel 7, and relatively upward, ascontrasted to the conventional long irons each having the head bodyintegrally combined with the hosel, both being formed of steel.Accordingly, the orbital radius R in swinging can be shortened, therebydecreasing moment of inertia. As a result, the weight proximate to aplayer's hand can be relatively increased so as to permit the bettercontrol of the balls B in striking them.

According to a first embodiment of the invention, as the head body 8having face 3 is formed of the material of the different specificgravity than that of the material for the hosel 7, the positions of thecenters of gravity G₁ and G₂ can be adjusted so as to change the momentsof inertia with respect to the rotational center approximated to theposition of player's shoulder, thereby permitting the exhibiting of theperformances, such as either elongating the travelling distance of ballsor better controlling of the balls B, corresponding to each iron number.

More specifically, for long irons, the material for the hosel 7 isthinner than that for the head body 8, wherey the travelling distance ofballs can be elongated. On the other hand, for short irons, the materialfor the hosel 7 is denser than that for the head body 8, whereby theballs B are allowed tobe better controlled. Thus, there can be provideda set of iron golf club heads that can exhibit the apparentlycontradictory performances.

In FIGS. 5 to 8 showing second and third embodiments of the invention,the same portions as those described in a first embodiment will bedesignated as common reference numerals, and their repeated detaileddescriptions will be omitted.

In a second embodiment, a head body 21 is connected with a hosel 22 byfitting or bonding the former to the latter. In this case also, for longirons, the material for the hosel 22 is thinner than that for the headbody 21, while for short irons, the material for the hosel 22 is denserthan that for the head body 21. An upper part of one side of the headbody 21 is formed with a mouting hole 23, into which is inserted aprotrusion 24 formed at a lower part of the hosel 22, which is fixed tothe mounting hole 23 with an adhesive (not shown), or may be pressedthereinto.

According to a second embodiment of the invention, suitable positions ofthe C. G. of the head 1 can be set, corresponding to short irons or longirons, in the same manner as a first embodiment. Further, as the headbody 21 is connected to the hosel 22 by means of bonding orpress-fitting, simplified connection therebetween can be realized.

Referring to FIGS. 7 and 8 showing a third embodiment, a head body 31comprises a face member 32 and a frame member 33 integrally providedalong an outer periphery of the face member 32. The face member 32 ismade of titanium or titanium alloy, while the frame member made of amaterial denser than that of the face member 32, such as berylliumcopper alloy or steel. A hosel 34, which is connected to the head body31 by screwing, bonding or press-fitting, is made of a material havingthe specific gravity different than that of the head body 31, i.e., theweight of the head body 31 divided by the volume thereof. In this casealso, for long irons, the material for the hosel 34 is thinner than thatfor the head body 31, while for short irons, the material for the hosel34 is denser than that for the head body 31.

According to a third embodiment of the invention, suitable positions ofthe C. G. of the head 1 can be set, corresponding to short irons or longirons, in the same manner as a first embodiment. Further, as the headbody 31 comprises the face member 32 and the frame member 33 denser thanthe face member 32, the weight of the face member 32 can be distributedtoward the periphery of the face member 32, thus enlarging a sweet area.

Next, a fourth embodiment of the invention will be explained withreference to FIGS. 9 to 11. An iron-type golf club head of thisembodiment comprises a head 41 and a shaft 42. The head 41 is formedwith a face 43 at its front suface, a recess 44 customarilly called"cavity" at its back surface, a sole 45 at its lower portion, a heel 46at a lower portion of one side thereof and a hosel 47 for connecting theshaft thereto at an upper portion of the same side thereof,respectively.

The head 41 comprises a head body 48 formed with aforesaid face 43,recess 44, sole 45 and heel 46, and the short-cylinder-like hosel 47formed from a material having a different specific gravity, said headbody 48 and the hosel 47 being formed in advance by forging, thenintegrally combined. The head body 48 has a flat abutting portion 49which is circularin plan view at its upper part of one side thereof, towhich is joined another flat abutting portion 50 of the same plansection formed at a lower part of the hosel 47. Then, the shaft 42 isinserted into a mounting hole 51 formed at the upper part of the hosel47.

For the long irons of the 1st iron to the 5th iron in the aforesaidTable 1, beryllium copper alloy (the specific gravity:approx. 8.2) orsteel (the specific gravity:approx. 7.9) is chosen as the material forthe head body 48, while titanium or titanium alloy (the specificgravity:approx. 4.5) for that for the hosel 47. Thus, the specificgravity of the material for the hosel 47 is smaller than that for thehead body 48.

On the other hand, for the short irons including the 6th to 9th irons,PW, SW and LW in the aforesaid Table 1, titanium ortitanium alloy (thespecific gravity:approx. 4.5) or steel (the specific gravity:approx.7.9) is chosen as the material for the head body 48, while berylliumcopper alloy (the specific gravity:approx. 8.2) for that for the hosel47. Thus, the specific gravity of the material for the hosel 47 isgreater than that for the head body 48. Incidentally, reference numeral52 designates so-called score lines formed on the face 43.

Next, the production method of the above structured golf club head willbe explained.

For joint between the head body 48 and the hosel 47, both of which beingformed from different material by forging, a pressing force F is appliedto the head body 48 and the hosel 47 with a central axis 49A of theabutting portion 49 aligned to another central axis 50A of the otherabutting portion 50, then relatively rotating the hosel 47 so as togenerate frictional heat between the abutting portions 49 and 50. Withthe frictional heat, the head body 48 can be joined to the hosel 47 viaa boundary surface 53. Then, the mounting hole 51 is formed coaxiallywith respect to the central axis 50A.

Next, the action of the above-structured golf club head will beexplained.

For long irons, the hosel 47 is made of material thinner than that forthe head body 48, whereby the center of gravity G₁ of the head 41 can bepositioned at the other side of thereof and lowered, as compared to theconventional golf club head having a head body integrally combined witha hosel, both being made of steel. Accordingly, an orbital radius inswinging is made larger, thereby increasing a moment of inertia.Consequently, a larger impact can be given golf balls to allow them totravel a longer distance.

For short irons, the hosel 47 is made of material denser than that forthe head body 48, whereby the center of gravity G₂ of the head 41 can bepositioned at one side thereof and raised, as compared to theconventional golf club head having a head body integrally combined witha hosel, both being made of steel. Accordingly, an orbital radius inswinging is made smaller, thereby decreasing a moment of inertia.Consequently, weight proximate to a player's hand can be relativelyincreased so as to permit the better control of the balls in strikingthem.

As above described, according to a fourth embodiment of the invention,the abutting portion 49 formed at the upper part of one side of the headbody 48 is allowed first to contact the other abutting portion 50 formedat the lower part of the hosel 47 then be relatively rotated whileapplying a pressing force thereto, whereby the frictional heat can begenerated. With the use of the frictional heat thus generated, frictionwelding can be carried out, so that an area affected by the heat in suchjoining process can be made relatively smaller whilst the connectionstrength at the boundary portion 53 is relatively greater, in additionto a noticeably short joining time per one joining process as well asimproved productivity.

Further, as the head body 48 with the face 43 and the hosel 47 are eachformed from material having the different specific gravities, thecenters of gravity G₁ and G₂ of the head 41 can be adjustably located,thereby changing the moment of inertia prescribed between the G₁, G₂ anda player's shoulder approximated to a rotational center in swinging,thereby permitting the exhibiting of the performances, corresponding toeach iron number, such as elongating the travelling distance of balls orbetter controlling of them.

FIGS. 12 and 13 show a fifth embodiment of the invention, while FIGS. 14to 16 show sixth to eighth embodiments respectively, in which the sameportions as described in a fourth embodiment will be designated ascommon reference numerals, and their repeated detailed descriptions willbe omitted.

In a fifth embodiment as illustrated by FIGS. 12 and 13, the mountinghole 51 is formed in advance in the hosel 47, coaxially with respect tothe central axis 50A. Then, a pressing force F is applied to the headbody 48 and the hosel 47 with a central axis 49A of the abutting portion49 aligned to the other central axis 50A of the other abutting portion50, then relatively rotating the hosel 47 so as to generate frictionalheat between the abutting portions 49 and 50. With the frictional heat,the head body 48 can be joined to the hosel 47 via the boundary surface53.

Besides the foregoing advantages, the golf club head of a fifthembodiment is advantageous in that as the mounting hole 51 is formed inadvance in the hosel 47, it can be more easily formed therein, prior tojoining the hosel 47 to the head body 48.

In a sixth embodiment as illustrated by FIG. 14, a pressing force F isapplied to the head body 48 and the hosel 47 with the central axis 49Aof the abutting portion 49 aligned to the other central axis 50A of theother abutting portion 50, then rotating both of the hosel 47 and thehead body 48 reversely with respct to each other, thus generatingfrictional heat between the abutting portions 49 and 50. With thus moreeffectively generated frictional heat, the head body 48 can be joined tothe hosel 47 via the boundary surface 53.

In a seventh embodiment as illustrated by FIGS. 15, a pressing force Fis applied to the head body 48 and the hosel 47 with the central axis49A of the abutting portion 49 aligned to the other central axis 50A ofthe other abutting portion 50, then laterally reciprocating the hosel 47relative to the head body 48, thus generating frictional heat betweenthe abutting portions 49 and 50. With thus more effectively generatedfrictional heat, the head body 48 can be joined to the hosel 47 via theboundary surface 53.

In an eighth embodiment as illustrated by FIG. 16, a pressing force F isapplied to the head body 48 and the hosel 47 in the same manner as theforegoing embodiments, then rotation-vibrating the hosel 47 relative tothe head body 48, thus generating frictional heat between the abuttingportions 49 and 50. With thus more effectively generated frictionalheat, the head body 48 can be joined to the hosel 47 via the boundarysurface 53.

Incidentally, the present invention should not be limited to theforegoing embodiments, but may be modified within a technical scope ofthe invention. For example, the difference in weight or the weight ratiobetween the head body and the hosel may be chosen in a manner likearithmetical progression or geometrical progression. Further, theaforesaid Table 1 only indicates the most standard values, and othervalues can be suitably chosen. In addition, in carrying out the frictionwelding, the head body can be rotated instead of rotating the hosel asdescribed in a fourth embodiment.

What is claimed:
 1. A production method for an iron-type golf club headhaving a head body defining a face at its front and a hosel provided atits one side for mounting a shaft thereto, which comprises the stepsof:forming said head body and said hosel from different material havingthe different specific gravities respectively; allowing one side of saidhead body to abut to said hosel, then joining said head body to saidhosel by means of a friction welding.
 2. A production method for aniron-type golf club head according to claim 1, wherein for short irons,said hosel is formed from a material denser than that of said head body,while for long irons, said head body is formed from a material denserthan that of said hosel.
 3. A production method for an iron-type golfclub head according to claim 2, wherein said step of the frictionwelding comprises the steps of:forming one abutting portion at an upperpart of said head body, while forming another abutting portion at alower end of said hosel; allowing the two abutting portions to contacteach other, then applying a pressing force thereto while rotating one ofthe abutting portions relative to the other.
 4. A production method foran iron-type golf club head according to claim 2, wherein said step ofthe friction welding comprises the steps of:forming one abutting portionat an upper part of said head body, while forming another abuttingportion at a lower end of said hosel; allowing the two abutting portionsto contact each other, then applying a pressing force thereto whilerotating the two abutting portions reversely with respect to each other.5. A production method for an iron-type golf club head according toclaim 2, wherein said step of the friction welding comprises the stepsof:forming one abutting portion at an upper part of said head body,while forming another abutting portion at a lower end of said hosel;allowing the two abutting portions to contact each other, then applyinga pressing force thereto while reciprocating one of the abuttingportions laterally relative to the other.
 6. A production method for aniron-type golf club head according to claim 2, wherein said step of thefriction welding comprises the steps of:forming one abutting portion atan upper part of said head body, while forming another abutting portionat a lower end said hosel; allowing the two abutting portions to contacteach other, then applying a pressing force thereto whilevibration-rotating one of the abutting portions relative to the other.